1. Field of The Invention
The present invention relates to the field of anatomical restoration dental implant systems. More particularly the present invention relates to the field of the design and construction of dental implants.
2. Description of The Prior Art
Dental implants are widely used in anatomical restoration dental operations or surgeries. They are used primarily for attaching various dental components to the jawbone of a patient. One of the inventors of the present invention is also the inventor and patentee of many patented dental restoration systems and dental components as disclosed in U.S. Pat. Nos. 5,035,619, 5,073,111, 5,145,372, 5,213,502 and 5,297,963. This invention is part of a constant desire and effort by the inventors to improve and advance dental restoration systems.
A typical conventional dental implant has a generally cylindrical shaped body which is to be imbedded in a patient's jawbone by first drilling a hole in the patient's jawbone and then inserting the implant into the hole. The implant is usually threadedly fitted or press-fitted in the hole.
Most conventional implants have a fixed bottom which has a definite dimension. Oftentimes when a hole in a patient's jawbone is improperly drilled, e.g., the hole is drilled too big, there will be a size discrepancy between the hole and the implant. This will result in loose implant in the jawbone and possible increased rate of implant loss.
One way to solve the problem of mismatch is to utilize an implant which has a split bottom with an expanding mechanism, so that once the implant is inserted into an oversized hole, the bottom of the implant can split and expand to better fit within the hole.
The following eight (8) patents are the closest prior art references which relate to dental implants with a split bottom:
1. U.S. Pat. No. 5,219,287 issued to Nishihara on Jun. 5, 1993 for "Artificial Dental Root Having Function of Natural Dental Root" (hereafter the "Nishihara Patent").
2. U.S. Pat. No. 5,004,421 issued to Lazarof on Apr. 2, 1991 for "Dental Implant and Method of Using the Same" (hereafter the "Lazarof Patent").
3. U.S. Pat. No. 4,588,381 issued to Caracciolo on May 13, 1986 for "Universal Pin for Oral Implantoprosthesis" (hereafter the "Caracciolo Patent").
4. U.S. Pat. No. 4,468,201 issued to Fukuyo on Aug. 28, 1994 for "Dental Endosseous Implant" (hereafter the "Fukuyo Patent").
5. U.S. Pat. No. 4,220,712 issued to Staffolani on Sep. 2, 1980 for "Dental Implant and Method of Inserting" (hereafter the "Staffolani Patent").
6. U.S. Pat. No. 4,011,602 issued to Rybicki et al. on Mar. 15, 1977 for "Porous Expandable Device for Attachment to Bone Tissue" (hereafter the "Rybicki Patent").
7. U.S. Pat. No. 3,708,883 issued to Flander on Jan. 9, 1973 for "Dental Implant and Method for Using the Same" (hereafter the "Flander Patent").
8. U.S. Pat. No. 3,579,831 issued to Stevens et al. on May 25, 1971 for "Bone Implant" (hereafter the "Stevens Patent").
The Lazarof Patent discloses a dental implant. The dental implant can be positively secured within a bore in a jawbone by an expander mechanism. The implant has an upper threaded portion and a lower skirt portion. The skirt portion is split into four separately expandable bone anchor segments. The expander mechanism includes an expander means which has an upper threaded portion and a lower frusto-conical portion. The expander means can be rotated by a removable Allen wrench by extending the Allen wrench through the internal bore of the implant. When the expander is rotated, its upper threaded portion is engaged with the internal threads of the implant which causes the expander means to move upwardly, which in turn causes its lower frusto-conical portion to engage with the four separately expandable bone anchor segments of the implant and causes them to expand outwardly.
The Caracciolo Patent discloses a "universal" pin for oral implantoprosthesis. The bottom part of the "universal" pin is split. In a first embodiment, the pin is hollow and a solid element is inserted from the top of the pin all the way towards the bottom, which causes the split bottom of the pin to expand outwardly. In a second embodiment, a wedge base is inserted from the bottom of the pin, which also causes the split bottom of the pin to expand outwardly. When the bottom part expands outwardly, the "universal" pin has a double taper configuration.
The Staffolani Patent discloses a dental implant with various shaped lower tips. The tips can be forced by the insertion of a pin to rotate out and upwardly into the bone.
The Rybicki Patent discloses an expandable cylinder for attachment to bone tissue. The expandable cylinder has splits which allows the cylinder to expand outwardly when a tapered pin is drawn into the cylinder by tightening a threaded nut.
The Flander Patent discloses a dental implant having a split bottom. An elongated shaft is extended through the implant. A small nut is threaded on the upper end of the shaft for "pulling" the shaft upwardly. The lower part of the shaft has a spreader end portion which acts as a wedge to cause the implant to expand when the shaft is pulled upwardly.
The remaining prior art patents are not as close and are discussed here briefly for reference.
The Nishihara Patent discloses an artificial dental root made of a shape-memorizing alloy capable of changing the apex morphology of the artificial root after implantation so as to stay in the jawbone. The Fukuyo Patent discloses a dental endosseous implant utilizing various deflectable legs which have shape-memory effects for securing the implant. The Stevens Patent discloses a bone implant having an axially extending notch at its bottom to provide a pair of springy threaded portions capable of resiliently flexing toward and away from each other so as to enhance the self-threading action of the implant.
From the above review it can be seen that the overall idea of utilizing an implant with split bottom to securely attach the implant to the jawbone has been disclosed. Various mechanisms have been disclosed by the prior art to achieve the purpose of causing the split bottom of the implant to expand. For example, in the Staffolani Patent and the first embodiment of the Caracciolo Patent, a solid shaft is inserted from the top of the implant to force the split bottom of the implant to expand outwardly, whereas in the Flander Patent and the Rybicki Patent, a solid shaft is drawn upwardly through the implant so that its wedge shaped bottom can cause the split bottom of the implant to expand outwardly.
Two prior patents have particularly disclosed the idea of using a separate small wedge to engage and expand the split bottom of the implant. The first is the Caracciolo Patent where a small wedge shaped base element is utilized in the second embodiment. This is a very modest and preliminary design and does not adequately satisfy the need for precise control in dental operations. The second, however, is the Lazarof Patent where an expander means is utilized which can be drawn upwardly by threading it on the internal surface of the implant and thereby causes the split bottom of the implant to expand outwardly. This is a much more detailed and sophisticated design.
However, there is a major drawback in the prior art dental implant with expandable bottom. For example, in the Lazarof Patent, the implant is first threaded into the jawbone, then the expander means is tightened by using an Allen wrench. This involves two separate manipulating steps to secure the implant to the patient's jawbone.
It is desirable to have a new design and construction of a dental implant with a split bottom which can be secured to the jawbone of a patient in one single step. It is desirable to design and construct an expanding mechanism which causes the expander to be automatically tightened when the implant is threaded into the jawbone.